Cotton insect control tools improve

Paul L. Hollis Farm Press Editorial Staff | Apr 02, 2003

Cotton producers have the best tools available for controlling insects than at any time in the history of synthetic chemicals. The challenge, says Auburn University Extension Entomologist Ron Smith, is knowing when these tools will pay for themselves.

“We have more and different chemicals that are very selective and specific,” says Smith. “Most of these are different classes of insecticides, meaning they work with different modes of action. This should be helpful in preserving this chemistry for the long-term.”

The problem, he adds, is that these new materials are expensive, and cotton markets have been in a prolonged price slump. “As a result, we probably aren't using as much of this chemistry as we should be using. The big job for growers in the future will be knowing when this chemistry is paying for itself. And there are many times when it will pay for itself,” says Smith.

Competition eventually could lower the prices of some of the new insecticides, he says. “But we haven't used enough of it in our part of the Cotton Belt to create any volume — a greater volume of use sometimes tends to lower the price. We haven't made many foliar insecticide sprays to cotton here in Alabama in the last two years, and other regions of the Cotton Belt are in the same situation,” says Smith.

Boll Weevil Eradication, Bt cotton and the depressed cotton market all have contributed to a lower spray environment, he says.

“Many times, growers in our state have not treated due to economic conditions. They've taken the damage rather than spending money. Hopefully, with the price appearing to be in somewhat of a turnaround situation, we'll come out of that mentality and try to make our best yields.

“We've been growing cotton in a defensive mode. It was hard to make a profit, but it was done that way for survival. The growers who stay in business will have to turn their attention to making the highest yields with the fewest inputs.”

The new chemistry also is very safe, he says. “This chemistry is the safest we ever could imagine — it's safe for humans and wildlife. In fact, it's so selective that sometimes we can take out caterpillar pests and leave lady beetles. We couldn't imagine doing something like that in the old days.

“It's so specific that sometimes it doesn't get all species of caterpillars. It's more effective on some than on others. Some of these materials work well on foliage-feeding caterpillars like armyworms but don't do so well on bollworms and budworms,” he says.

Smith predicts there will be no more broad-spectrum chemistry in the cotton insect arena. “That's bad from a management standpoint but good for the environment. Most environmental problems were the result of long residuals from broad-spectrum materials.”

New cotton insect chemistry must be applied precisely and a timely manner, he says. They work either on caterpillar pests or on bugs or sucking pests, with no crossover activity.

Turning to caterpillar pests, Smith says the product Tracer has been available now for several years. “It's a tremendous product for resistant tobacco budworms, which we weren't able to control before it became available. In addition, we've had Steward for a couple of years. Intrepid works on foliage-feeding pests, and Denim probably will be labeled for use this season. These products represent four unique modes of action, so we can swap them around and preserve them for the future.”

New chemistry also is available for bugs and sucking pests, he continues, including Trimax, Intruder and Centric.

“Each of these works great on aphids. When we get into bug pests — such as plant bugs and stink bugs — some have an advantage over others. Growers need to know how each of these products performs and match them to the pest they're targeting in the field. Some are a little less expensive than the others. If growers have aphids and plant bugs, they'll have to spend a little more money and use materials that'll work on both.”

New chemistries are in the pipeline that will offer even more modes of action, says Smith. New genetic technologies also are in development.

“Beginning in 2004, Bollgard won't be the only game in town. Even this year, we'll have Bollgard II with a second Bt gene that works at a different site in the insect's gut, making it more difficult to develop resistance. Bollgard II will work on all caterpillar pests, including armyworms. By 2005, Bollgard will be phased out of the market and Bollgard II will replace it.

“We always feared we'd get resistance before we made it to the second stage of the technology. Another company — Dow — is working with a variety that also has two Bt genes. It's not the Monsanto Bt gene, and it performs similarly to Bollgard II, which means there will be competition. That could lower the cost of the technology. We started working last year with Syngenta, and they're looking at a different type of protein. They may have something by 2004. So in a few years, several companies will have genetic technology, and that'll be good for farmers.”

Rather than having broad-spectrum, dominant insect pests requiring multiple applications, growers now are confronted with “sporadic pests,” says Smith.

“We're into a stage where we do more monitoring than treating. For example, we may have one field in Alabama with stands threatened by vegetable weevils, which never has been viewed as a pest. Last year, we saw three-cornered alfalfa hoppers. Grasshoppers also have become a more significant early season pest.

“Several things have occurred over a short period of time to cause these changes. We eliminated the boll weevil, and we introduced genetically altered cotton. We've also gone more to conservation-tillage. Some of these sporadic pests are coming in with reduced tillage, and they're out there in the stubble feeding on the burned-down vegetation.”

Scouting for cotton insects has evolved in recent years, he says, to where it now requires more training and expertise. “It's more difficult to train a scout to look for 15 potential pests than to focus on one or two, like bollworms or weevils. So, it has made scout training much more difficult.”

The Extension Service still trains cotton insect scouts, but Smith says he isn't comfortable with these scouts going into the fields after one day's training.

“The scouts we train need to work under an experienced supervisor on a daily basis, and that means working with a consultant or other experienced person. That's the trend of the future.”

Scouting techniques have been modified, he says, to meet the demands of sporadic and emerging insect pests.

“We've modified our thresholds for when growers should treat for certain pests. For example, we had to develop stinkbug thresholds from scratch. We started with a certain number of stinkbugs per row feet. But we eventually saw that you can't catch stinkbugs in waist-high cotton.

“Now, we've identified the exact size of the boll they prefer. We slice those bolls and look for internal damage — about a quarter-size in diameter.”